Preparation method and application of laser-induced graphene oxide nanofiber membrane

Abstract

The invention relates to the technical field of flexible sweat sensors, in particular to a preparation method and application of a laser-induced graphene oxide nanofiber membrane. Comprising the following steps: S1, preparing a graphene oxide nanofiber membrane through an electrostatic spinning process; s2, carrying out laser reduction on the graphene oxide nanofiber membrane, namely engraving an electrode pattern on the graphene oxide nanofiber membrane by adopting a laser, and reducing on the electrode pattern of the graphene oxide nanofiber membrane to generate an LGNF electrode; s3, performing hydrophobic treatment on the graphene oxide spinning fiber membrane; s4, catalytic particles and enzyme are modified on the LGNF electrode, and the laser-induced graphene oxide nanofiber membrane is prepared. The method is simple, efficient, convenient and easy to implement, low in requirement for manufacturing equipment and capable of well achieving mass production, and the sensor prepared through the method can spontaneously absorb sweat to the surface of the electrode to achieve sweat monitoring, so that the hydrophilicity of graphene can be effectively improved, and the electrochemical performance of graphene is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sweat sensors, and in particular to a preparation method and application of a graphene nanofiber flexible sensing electrode. Background Art

[0002] Wearable electronic devices with excellent breathability can bring a comfortable wearing experience and contribute to continuous monitoring of biological signals for a longer time. Although significant progress has been made in optimizing the mechanical and electrical properties of these wearable devices, their widespread adoption and clinical application still face some obstacles. A major challenge is the poor permeability of electronic materials / devices, resulting in the accumulation of sweat at the skin-device interface after operation for a period of time. This obstacle not only causes thermal physiological discomfort to users, but also reduces the quality of the collected signals and the adhesion characteristics, thus hindering long-term accurate signal monitoring.

[0003] Breathable electronic devices based on the structure of ultra-thin porous nanofibers can passively or actively discharge gases, vapors and sweat through their nano-openings. Therefore, they provide a user-friendly interface between the skin and the device, ensuring more stable signal acquisition during long-term medical monitoring even when sweating. Conventional laser-induced graphene substrates are flexible sensor devices made of polyimide (PI) that do not match the human modulus; PI-based LIG usually has more graphene defects, the electrode quality is not high, and it is difficult to accurately detect low-concentration targets; the PI-based LIG sensing unit is fragile and difficult to adapt to complex human skin conditions such as bending and stretching when directly contacting the human skin; the PI substrate cannot balance comfort and performance at the same time, and there is also the problem of unstable signals under sensor strain. In addition, the most advanced wearable electronic devices include more complex functional sensors, circuits and modules for signal acquisition, processing and transmission. Therefore, achieving a highly integrated multifunctional wearable electronic device with a breathable form is still a significant challenge. Therefore, it is urgently needed to be solved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method and application of a laser-induced graphene nanofiber membrane. This method uniformly prepares a graphene oxide nanofiber membrane by electrospinning a graphene oxide aqueous solution, and simultaneously reduces the graphene oxide while laser engraving an electrode pattern on the surface of the graphene oxide nanofiber membrane through a laser-induced graphene process, endowing it with excellent conductivity, preparing an LGNF electrode, which can be attached to the surface of the human skin and spontaneously transport the sweat on the skin surface to the surface of the electrode for sensing and monitoring, perfectly integrating functions such as breathability, sweating, sensing, and self-adhesion, and constructing an excellent wearable flexible sensor that meets the needs of users.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows. A preparation method and application of a laser-induced graphene oxide nanofiber membrane, characterized by comprising the following steps:

[0006] S1. Prepare a graphene oxide nanofiber membrane (i.e., GONF membrane) through an electrospinning process;

[0007] S2. Laser reduce the graphene oxide nanofiber membrane: Engrave the electrode pattern onto the graphene oxide nanofiber membrane by laser engraving, and during the engraving of the electrode pattern, laser-induced graphene nanofiber electrodes (i.e., LGNF electrodes) are reductively generated on the electrode pattern;

[0008] S3. Hydrophobically treat the non-electrode region on the side of the graphene oxide spun fiber membrane where the laser-induced graphene nanofiber electrodes (LGNF electrodes) are generated;

[0009] S4. Modify catalytic particles and enzymes on the LGNF electrodes of the graphene oxide spun fiber membrane: Electrochemically deposit Prussian blue on the LGNF electrodes by an electrochemical deposition method, and drop 3 - 5 μL of glucose oxidase on the surface of the LGNF electrodes to prepare a laser-induced graphene oxide nanofiber membrane.

[0010] The catalytic particles and enzymes modified on the LGNF electrodes form a sensing layer for detecting glucose in sweat.

[0011] Preferably, in step S1, the process of preparing the graphene oxide nanofiber membrane by the electrospinning process includes:

[0012] S11. Introduce sodium polyacrylate (PAS) with a concentration of 1×10 8 g / mol and the co-surfactant Triton X-100 into the GO aqueous dispersion to obtain a mixed solution;

[0013] S12. Use a stirrer to stir the mixed solution at a speed of 2000 rpm for 30 minutes until it is completely homogeneous to obtain a black viscous GO spinning material;

[0014] S13. Pour the prepared GO spinning material into a 20 mL syringe and extrude it through a metal nozzle at a speed of 0.018 mL / min.

[0015] S14. After continuous electrospinning for 36 hours, manually peel the spun graphene oxide nanofiber membrane from the copper mesh and store it in a vacuum drying oven.

[0016] Preferably, during the electrospinning process, the applied voltage is 18 kV, the distance between the metal nozzle and the receiving drum is maintained at 15 cm, the temperature is 45 °C, and the humidity is 10% to 15%.

[0017] Preferably, in step S1, the thickness of the graphene oxide nanofiber membrane is 40 - 50 μm.

[0018] Preferably, in step S2, the process of laser-induced treatment on the graphene oxide nanofiber membrane includes:

[0019] S21. Attach the graphene oxide nanofiber membrane to a customized vacuum dish;

[0020] S22. Then place the vacuum dish in a laser engraving machine, import the pre-designed electrode pattern into the engraving graphics software, and adjust the distance between the laser spot of the laser and the graphene oxide nanofiber membrane;

[0021] S23. Introduce nitrogen into the vacuum dish, start the laser to begin laser engraving, the electrode pattern is engraved onto the graphene oxide nanofiber membrane, and a laser-induced graphene nanofiber electrode (LGNF electrode) is generated by reduction at the engraved electrode pattern.

[0022] Preferably, in step S2, the laser used for laser engraving is a CO 2 laser, and the power of the laser is 6 - 7.5 W, the moving speed of the laser head is 350 - 400 mm / s, and the laser focal length is 8 - 10 cm.

[0023] Preferably, in step S3, the solution used for hydrophobic treatment is a n-hexane solution containing octadecyltrichlorosilane; the concentration of the hydrophobic solution is 1 - 5 wt%.

[0024] Preferably, in step S3, cyclic voltammetry is used for electrodeposition, and the controlled potential range for electrodeposition is -0.2 V to 0.6 V, and the deposition time is 300 s.

[0025] Preferably, during the laser reduction process of the laser-induced graphene nanofiber electrode, a hydrophilic-to-hydrophobic gradient structure is formed on the laser-induced graphene nanofiber electrode.

[0026] The graphene oxide nanofiber membrane is used to attach to the surface of human skin. Since the contact surface between the graphene oxide nanofiber membrane and the human body has strong hydrophilicity, while the sensing layer of the laser-induced graphene nanofiber electrode has hydrophobicity, after the graphene oxide nanofiber membrane attaches to the surface of human skin, the liquid can first quickly diffuse at the contact surface between the graphene oxide nanofiber membrane and the human body. At the same time, due to the strong capillary force of the graphene oxide nanofiber membrane, it can lead the liquid to break through the hydrophobic force and spontaneously absorb and pump the sweat to the laser-induced graphene nanofiber electrode.

[0027] Preferably, the laser-induced graphene oxide nanofiber membrane prepared by the method for preparing a laser-induced graphene oxide nanofiber membrane is used to fabricate a graphene nanofiber flexible sensor, and the graphene nanofiber flexible sensor is used for quantitative analysis and / or qualitative analysis of glucose in sweat.

[0028] The beneficial effects of the present invention are embodied in:

[0029] (1) The method provided by the present invention is the first to combine electrospun graphene oxide fibers with a laser engraving process. Compared with most graphene sensors based on PI substrates in the field, the raw material of the present invention is graphene oxide, and after laser reduction, it has less defects and better quality graphene, with a low DG ratio of up to 0.11.

[0030] (2) The graphene oxide nanofiber membrane prepared by the electrospinning process adopted by the method provided by the present invention converts the 2D graphene sheet morphology into 1D nanofibers, and naturally has the material characteristics of being soft and having a porous microstructure, thus ensuring the breathability and comfort required by the wearer's skin, and making the sensor match the human modulus. This not only has excellent advantages compared with the plastic PI substrate, but also can solve the problem that the PI substrate is brittle and easy to break.

[0031] (3) The method provided by the present invention adopts a laser-induced technique, and through a transient high-temperature and high-pressure environment, it can instantaneously achieve highly reduced graphene oxide, giving the laser-induced graphene nanofiber electrode high conductivity. High-conductivity graphene can enhance the signal conduction efficiency, shorten the response time, lower the detection limit, and improve the stability and repeatability of the device.

[0032] (4) The LGNF electrode prepared by the method provided by the present invention forms a gradient structure from hydrophilic to hydrophobic from the bottom to the top. This is because the laser intensity is attenuated as the thickness of the GONF film increases, resulting in a lower reduction degree of graphene in the GONF film. The higher the reduction degree of graphene, the more hydrophobic it is. Therefore, the top of the LGNF electrode is hydrophobic, and the bottom is hydrophilic. When in use, the GONF film contacts the surface of the human skin. When the liquid contacts the GONF film, due to the strong hydrophilicity of the GONF film, the liquid can quickly spread on the contact surface. The GONF film transfers the liquid to the bottom of the LGNF electrode. At the same time, due to the super strong capillary force of the nanofibers of the GONF film, the liquid can be guided from the bottom of the LGNF electrode along the gradient structure of the LGNF electrode through the hydrophilic-hydrophobic boundary of the LGNF electrode and reach the sensing layer. Different from the general perception that the liquid of the Janus film can only be transported from the hydrophobic layer to the hydrophilic layer, the present invention realizes the liquid transportation from the hydrophilic layer to the hydrophobic layer. The whole process realizes the spontaneous induction of rapid pumping of sweat to the electrode sensing area for detection, avoiding direct contact between the electrode and the human skin, without the need for complex device design, and improving the detection speed. Description of the Drawings

[0033] Figure 1 It is the process diagram of preparing the GONF film in the present invention;

[0034] Figure 2 It is the SEM diagram of the GONF film in the present invention;

[0035] Figure 3 It is the laser-induced customized vacuum dish diagram in the present invention;

[0036] Figure 4 It is the SEM diagram of the LGNF electrode in the present invention;

[0037] Figure 5 It is the SEM diagram of a single fiber of the LGNF electrode in the present invention;

[0038] Figure 6 It is the diagram of the relationship between the laser parameters and the conductivity of the LGNF electrode in the present invention;

[0039] Figure 7 It is the Raman comparison diagram of the three surfaces of GONF, LGNF-Top, and LGNF-Bottom in the present invention;

[0040] Figure 8 It is the diagram of exploring the influence of different parameters on the Raman and conductivity of the LGNF electrode in the present invention;

[0041] Figure 9 It is the vertical scale gradient structure diagram of the laser-induced graphene oxide nanofiber film prepared in the present invention. Detailed Embodiments

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] As Figures 1-9 shown, the present invention provides a preparation method and application of a laser-induced graphene oxide nanofiber membrane. As Figure 9 shown, a gradient structure from hydrophilic to hydrophobic is formed from the back surface to the front surface of the LGNF electrode prepared by the method provided by the present invention. This is because the laser intensity is attenuated as the thickness of the GONF membrane increases, so that the reduction degree of graphene in the GONF membrane becomes lower and lower at the same time. The higher the reduction degree of graphene, the more hydrophobic it is. Therefore, the surface of the LGNF electrode is hydrophobic and the back surface of the LGNF electrode is hydrophilic.

[0044] Example 1

[0045] As Figure 1 shown, an electrostatic spinning process is used to prepare a graphene oxide nanofiber membrane (i.e., GONF membrane). The electrostatic spinning process includes:

[0046] 1) To achieve electrostatic spinning of GO, we introduce sodium polyacrylate (PAS) with an extremely high molecular weight (~1*10 8 g / mol) and the co-surfactant Triton X-100 into the GO aqueous dispersion. The addition of PAS and Triton X-100 adjusts the rheological properties and surface tension of the GO coating. The mass ratio of the GO aqueous solution to the polymer PAAS is 1:1.

[0047] 2) Stir with a stirrer at 2000 rpm for 30 minutes until completely uniform to obtain a black viscous GO spinning material.

[0048] 3) Pour the prepared spinning material into a 20 mL syringe and extrude it through a metal nozzle at a speed of 0.018 mL / min. During the electrostatic spinning process, the applied voltage is 18 kV, the distance between the metal nozzle and the receiving drum is kept at 15 cm, the temperature is 45 °C, and the humidity is 10% to 15%.

[0049] 4) After continuous electrostatic spinning for 36 hours, the spun GONF membrane is manually peeled off from the copper mesh and stored in a vacuum drying oven.

[0050] To prove the successful preparation of the GONF film, the surface morphology of the GONF film prepared in Example 1 was characterized. The prepared GONF film was attached to the SEM sample stage, and conductive glue was used to connect the two ends of the film to the sample stage. Gold was sprayed on the electrodes, and then the electrospun fibers were observed under a scanning electron microscope. The results are as Figure 2 shown. It can be seen from the SEM characterization that the fiber microstructure of the GONF film without laser etching shows the typical morphology of GO / PAS nanofibers with a diameter of about 500 nm. Single fibers show standard graphene wrinkles, and the presence of PAS causes cross-linking between single fibers, forming an interconnected network. The further introduced Triton surfactant weakens the tendency of wire breakage during the electrospinning process by reducing the surface tension. The pictures show that we have achieved the topological transformation from planar graphene to 1D nanofibers by electrospinning and obtained continuous pure nanofibers.

[0051] Example 2

[0052] The process of laser-induced graphene oxide nanofiber film includes:

[0053] First, the GONF film was attached to a customized vacuum dish, as Figure 3 shown. The upper cover of the vacuum dish is a customized zinc selenide glass that can transmit 10.6 μm CO2 laser. The left and right are the air inlet and outlet respectively. Then the vacuum dish was placed in a laser engraving machine. The pre-designed electrode pattern was imported into the engraving graphics software. The distance between the laser spot and the GONF film was adjusted so that its best focal length was on the GONF film. Nitrogen was introduced, and the equipment was started to start laser engraving. In a very short time, a laser-induced graphene nanofiber electrode (i.e., LGNF electrode) was regenerated on the electrode pattern.

[0054] To prove the successful preparation of the LGNF electrode, the surface morphology of the laser-induced graphene oxide electrospun fiber film prepared in Example 2 was characterized. The prepared laser-induced graphene oxide electrospun fiber film was attached to the SEM sample stage, and conductive glue was used to connect the two ends of the film to the sample stage. Gold was sprayed on the electrodes, and then the electrospun fibers were observed under a scanning electron microscope. The results are as Figure 4 shown. The fiber microstructure of the laser-induced graphene nanofiber electrode (i.e., LGNF electrode) after laser etching can be clearly observed. Due to the transient high temperature and high pressure of the infrared laser, single graphene fibers are instantly reduced, releasing a large amount of gases (N 2 , CO, etc.), breaking through the original wrinkled surface of single fibers and forming flocculent fibers. After experimental optimization, nitrogen protection of the laser-induced graphene oxide electrospun fiber film was selected, so that the laser-induced graphene oxide electrospun fiber film was not burned in the high temperature and high pressure environment. Observing single fibers at high magnification, as Figure 5As shown, the cross-section and surface of the fibers of the present invention (i.e., the LGNF electrode) have become a hollow porous structure due to gas release. This is a completely new graphene fiber morphology, and the high specific surface area brought by the porous structure is very helpful for improving the electrochemical sensing performance.

[0055] Example 3

[0056] As the core material of the sensor, the surface quality and performance of the laser-induced graphene nanofiber electrode have an important impact on the performance of the sensor. In this example, the single-factor test method is used to study the effects of parameters such as laser power, scanning speed, and scanning times on the quality and performance of the laser-induced graphene nanofiber electrode. The test methods include:

[0057] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was explored.

[0058] The parameters of the laser in this example are: the laser power is 7.5 W, and the scanning speed is 100 mm / s.

[0059] Example 4

[0060] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was explored.

[0061] The parameters of the laser in this example are: the laser power is 7.5 W, and the scanning speed is 200 mm / s.

[0062] Example 5

[0063] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was explored.

[0064] The parameters of the laser in this example are: the laser power is 7.5 W, and the scanning speed is 300 mm / s.

[0065] Example 6

[0066] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was explored.

[0067] The parameters of the laser in this example are: the laser power is 7.5 W, and the scanning speed is 400 mm / s.

[0068] Example 7

[0069] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was investigated.

[0070] In this example, the parameters of the laser are as follows: the laser power is 7.5 W, and the scanning speed is 500 mm / s.

[0071] Example 8

[0072] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was investigated.

[0073] In this example, the parameters of the laser are as follows: the laser power is 6.5 W, and the scanning speed is 400 mm / s.

[0074] Example 9

[0075] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was investigated.

[0076] In this example, the parameters of the laser are as follows: the laser power is 7.5 W, and the scanning speed is 400 mm / s.

[0077] Example 10

[0078] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode was investigated.

[0079] In this example, the parameters of the laser are as follows: the laser power is 9 W, and the scanning speed is 200 mm / s.

[0080] Example 11

[0081] The specific steps are the same as those in Example 2, except that the influence of CO 2 laser parameters on the performance of the laser-induced graphene nanofiber electrode (i.e., LGNF electrode) was investigated.

[0082] In this example, the parameters of the laser are as follows: the laser power is 10 W, and the scanning speed is 200 mm / s.

[0083] Starting from a laser power of 5 W, the power was gradually increased, and starting from 100 mm / s, the scanning speed was decreased. The conductivity of the LGNF electrode under each parameter was tested in sequence, as Figure 6As shown, the present invention finds that when the laser power is 7.5 W and the scanning speed is 100 mm / s, the conductivity of the laser-induced graphene nanofiber electrode (i.e., the LGNF electrode) is as high as 5681 S / m. However, at this time, the LGNF electrode is damaged due to the high photothermal effect. After multiple tests, considering the conductivity and the quality of the electrode, the laser parameters are determined to be a power of 7.5 W and a scanning speed of 400 mm / s.

[0084] Using the single-factor experiment method, Raman spectroscopy analysis was carried out on the LGNF electrodes under different laser parameters, and the results are as Figure 8 shown. Under the Raman spectra of each sample in Figure 8 , peaks (D, G, and 2D peaks) appeared near 1340 cm-1, 1580 cm-1, and 2700 cm-1. This indicates that these products are graphene. When the laser speed was gradually increased from 100 mm / s to 500 mm / s, the ID / IG value reached the lowest of 0.045 at 200 mm / s. As the scanning speed increased, the D / G ratio gradually increased, but the change was small. The conductivity was relatively high in the range of 300 mm / s to 400 mm / s. When the laser power was increased from 6.5 W to 10 W, the ID / IG value gradually decreased, indicating that the surface defects of the laser-induced graphene nanofiber electrode for laser induction gradually decreased with the increase of the laser power. The conductivity was relatively high in the range of 7 W to 9 W. In summary, the Raman spectroscopy results are consistent with the SEM image results. Considering the conductivity of the LGNF electrode and the quality of the LGNF electrode, the laser parameters are determined to be a power of 7.5 W and a scanning speed of 400 mm / s.

[0085] Example 12

[0086] The specific steps are the same as those in Examples 2 and 3. The difference is that the formation of the internal gradient structure of the laser-induced graphene nanofiber electrode (i.e., the LGNF electrode) by the laser induction technique was explored.

[0087] Since the actual CO2 laser cannot completely penetrate the graphene oxide nanofiber membrane (GNF membrane), the laser intensity will decay with the membrane thickness of the GNF membrane, resulting in a gradual decrease in the carbonization intensity of the LGNF from the surface to the bottom, as Figure 7As shown, it was found by Raman that GONF, LGNF-Top and LGNF-Bottom exhibited different ratios of D peak to G peak. The ID:IG of GONF was approximately 0.68, the ID:IG of LGNF-Top was approximately 0.11, and the ID:IG of LGNF-Bottom was approximately 0.43. Thus, it can be seen that the degree of carbonization from low to high was GNF < LGNF-Bottom < LGNF-Top, preliminarily verifying the existence of the gradient structure. Further, the LGNF electrode was characterized by XPS. The carbon-oxygen ratio of LGNF-Top was always around 12.42, indicating that the carbon content on the upper surface of the LGNF electrode was higher and the degree of carbonization was higher. As the film thickness of LGNF-Bottom increased from 10 μm to 40 μm, the carbon-oxygen ratio decreased from 12 to 3, indicating that the carbon content at the bottom of the LGNF electrode became less and less with the increase in thickness, indicating that the reduction effect of the laser on the bottom of the electrode became smaller and smaller, verifying the formation of the gradient structure.

[0088] Example 13

[0089] The specific steps were the same as those in Examples 2 and 3, except that the effect of the gradient structure of the LGNF electrode on liquid transport was explored. The method included:

[0090] Example 4 had confirmed the existence of the internal gradient structure of the LGNF electrode. To explore the influence of the gradient structure on the direction of the liquid when it contacted the lower surface of the electrode, 1 mL of water was taken in a 5 mL syringe, and the liquid droplet was continuously extruded to contact the back of the LGNF. The present invention found that the liquid quickly and spontaneously transported from LGNF-Bottom to LGNF-Top, that is, the LIG conductive sensing layer, within 6.198 s.

[0091] Example 14

[0092] The laser-induced graphene nanofiber membrane prepared by the present invention is used to fabricate a graphene nanofiber flexible sensor, and the graphene nanofiber flexible sensor is used for quantitative analysis and / or qualitative analysis of glucose in sweat.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a laser-induced graphene oxide nanofiber membrane, characterized in that: The following steps are involved: S1. Preparation of graphene oxide nanofiber membrane by electrospinning process; S2. Laser reduction of the graphene oxide nanofiber membrane: engraving an electrode pattern onto the graphene oxide nanofiber membrane by laser engraving, and reducing the electrode pattern to generate a laser-induced graphene nanofiber electrode during the engraving process of the electrode pattern; S3, performing a hydrophobic treatment on a non-electrode area on one side of the laser-induced graphene nanofiber electrode generated by the graphene oxide spinning fiber membrane; S4. Modifying catalytic particles and enzymes on the laser-induced graphene nanofiber electrode of the graphene oxide nanofiber membrane: Prussian blue was electrodeposited on the electrode by an electrochemical deposition method, and glucose oxidase was added dropwise on the electrode surface to prepare a laser-induced graphene oxide nanofiber membrane.

2. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S1, the process of preparing graphene oxide nanofiber membrane by electrospinning process includes: S11, 1×10 8 g / mol sodium polyacrylate and auxiliary surfactant Triton X-100 were introduced into GO aqueous dispersion to obtain a mixed solution; S12, stirring the mixed solution at a speed of 2000 rpm for 30 minutes to obtain a GO spinning material; S13, pouring the prepared GO spinning material into a 20 mL syringe and extruding it through a metal nozzle at a speed of 0.018 mL / min; S14. After continuous electrospinning for 36 hours, the spun graphene oxide nanofiber membrane was manually peeled off from the copper mesh and stored in a vacuum drying oven.

3. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 2, characterized in that: During the electrospinning process, the applied voltage was 18 kV, the distance between the metal nozzle and the receiving roller was maintained at 15 cm, the temperature was 45 °C, and the humidity was 10% to 15%.

4. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S1, the thickness of the graphene oxide nanofiber membrane is 40-50 μm.

5. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S2, the process of laser inducing the graphene oxide nanofiber membrane includes: S21, attaching the graphene oxide nanofiber membrane to a customized vacuum dish; S22, placing the vacuum dish in a laser engraving machine, importing the pre-designed electrode pattern into the engraving graphics software, and adjusting the distance between the laser spot of the laser and the graphene oxide nanofiber film; S23. Nitrogen is introduced into the vacuum dish, and the laser is started to start laser engraving. The electrode pattern is engraved on the graphene oxide nanofiber membrane, and the engraved electrode pattern is reduced to generate a laser-induced graphene nanofiber electrode.

6. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 5, characterized in that: In step S2, the laser engraving adopts a CO2 laser, and the laser power is 6-7.5W, the laser head moving speed is 350-400mm / s, and the laser focal length is 8-10cm.

7. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S3, the hydrophobic solution used for the hydrophobic treatment is a n-hexane solution containing octadecyltrichlorosilane; the concentration of the hydrophobic solution is 1-5 wt%.

8. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S4, the electrodeposition is carried out by cyclic voltammetry, and the controlled potential range of the electrodeposition is -0.2V to 0.6V, and the deposition time is 300s.

9. The method for preparing a laser-induced graphene oxide nanofiber membrane according to claim 1, characterized in that: In step S2, a gradient structure from hydrophilic to hydrophobic is formed on the laser-induced graphene nanofiber electrode during the laser reduction process.

10. The laser-induced graphene oxide nanofiber membrane prepared according to the method for preparing the laser-induced graphene oxide nanofiber membrane according to any one of claims 1 to 9 is used to make a graphene nanofiber flexible sensor, and the graphene nanofiber flexible sensor is used to perform quantitative and / or qualitative analysis of glucose in sweat.

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